The present invention relates to a magnetoresistive effect head having laminations of a magnetoresistive effect head as a reproducing head and an inductive head as a recording head.
As the recording medium size is scaled down and increases in capacity, a relative speed between the magnetic head as the reproducing head and the magnetic recording medium is required to be small. In this circumstances, an expectation of the magnetoresistive effect head has been on the increase as the reproducing output of the magnetoresistive effect head is independent from the relative speed between the head and the magnetic recording medium. Such expected magnetoresistive effect head is, for example, disclosed in IEEE Transaction On Magnetics 7, No. 6, 1990, p. 150, "A Magnetoresistivity Readout Transducer".
FIG. 1 is a fragmentary cross sectional elevation view illustrative of a conventional magnetoresistive effect head having laminations of a magnetoresistive effect head as a reproducing head and an inductive head as a recording head in a direction from an air bearing face which faces to the surface of the magnetic recording medium.
The conventional magnetoresistive effect composite head has a magnetoresistive effect head portion 56 as a reproducing head and an inductive head portion 66 as a recording head. The magnetoresistive effect head portion 56 comprises a sandwiching structure, wherein a magnetoresistive effect element 54 is sandwiched by first and second magnetic isolation layers 581 and 582 which are further sandwiched by first and second magnetic shielding layers 50 and 52. The magnetoresistive effect element 54 comprises a center region 541 capable of sensing magnetic and first and second side regions 542 and 543 which are positioned on opposite sides of the center region 541 for supplying currents and a vertical bias magnetic field to the center region 541. The inductive head portion 66 comprises a magnetic gap 64 sandwiched by first and second magnetic pole layers 60 and 62. The first magnetic pole layer 60 of the inductive head portion 66 commonly serves as the second magnetic shielding layer 52. The first and second magnetic pole layers 60 and 62 have thin film coils. The magnetoresistive effect head portion 56 and the inductive head portion 66 are unitary formed with each other in the form of a single composite head.
It is required that the magnetic anisotropy of the first and second magnetic pole layers 60 and 62 be directed along an arrow mark 68 which is parallel to the width direction of the second magnetic pole layer 62 in order to increase the recording characteristic under high frequency conduction. The direction parallel to faces of the first and second magnetic pole layers 60 and 62 and parallel to the air bearing face is the easy axis of magnetization. As a result, the recording magnetic field is generated by magnetization rotation in a direction of a hard axis of magnetization, for which reason a large magnetic field is generated even under a high frequency condition.
In the Japanese laid-open patent publication No. 5-1821145, to improve the recording characteristic, the magnetic pole layer comprises laminations of a magnetic material and an insulation material to suppress generation of an eddy current for the purpose of reduction in an eddy current loss in a high frequency range. In this conventional method, however, it is not ensured that the recording magnetic field is generated by the magnetization rotation in a direction along the hard axis. Accordingly, even when the eddy current loss is suppressed, the necessary intensity of the magnetic field for recording into the magnetic recording medium can not be obtained.
In the prior art, the width "Lx" of the first magnetic pole layer 62 is relatively wide in relation to the height "Ly" of the first magnetic pole layer 62, wherein the width "Lx" of the first magnetic pole layer 62 substantially defines the track width of the magnetic recording. If, for example, a NiFe magnetic pole layer 62 is formed by electrodeposition, the desired magnetic anisotropy can be formed by formation of the NiFe layer under application of the magnetic filed in the direction along the arrow mark 68.
In recent years, however, as the high density of the magnetic recording medium or magnetic disc is promoted, the width "Lx" of the first magnetic pole layer 62 becomes narrower in relation to the height "Ly" of the first magnetic pole layer 62. As a result, even if the NiFe layer is formed under the application of the magnetic filed in the direction along the arrow mark 68, then the magnetic anisotropy may be directed either in a direction vertical to the air bearing surface as shown in FIG. 2A by an arrow mark 70 or in another direction along the height direction of the first magnetic pole layer 62 as shown in FIG. 2B by an arrow mark 72 due to anisotropy of the shape. This unstability of the direction of the magnetic anisotropy causes a deterioration of the recording characteristic in high frequency range and a reduction in yield of the manufacturing of the head.